Haven't messed around with my Xterra for a while because of health problems but got enough energy the other day to crawl around under my Off Road Xterra to look for anything obvious that could be making the groaning sounds in the back. Nothing. I did discover that my Off Road has less ground clearance than my stock 2000 XE 4x4. I don't care what the stats say. It was a tight fit under there especially in the front, and I've actually lost weight since I had the 2000 Xterra. Those skid plates are a joke, too, and I was not impressed with build quality in general.